1. Field of the Invention
The present invention relates to a frame and a double-sided emitting backlight module using the same.
2. General Background
Most portable electronic devices such as laptops, notebook computers, mobile phones, and game devices have flat panel displays (FPDs) as viewing screens, quite unlike the bulky cathode-ray-tube (CRT) monitors of, say, conventional desktop computers. Users of the portable electronic devices still expect the viewing screens to provide performance equal to that of CRT monitors. To meet this demand, computer manufacturers have sought to build FPDs offering superior resolution, color, and contrast, while at the same time requiring minimal power consumption. Liquid crystal displays (LCDs) are one type of FPD which satisfy these expectations. However, the liquid crystals of an LCD are not self-luminescent. Rather, the LCD needs a backlight module which offers sufficient luminance (brightness) in a wide variety of ambient light environments.
Nowadays both single-sided and double-sided LCD displays are in widespread use in various electronic devices. Referring to FIG. 4, a conventional double-sided LCD is shown. The LCD 100 includes a backlight module (not labeled), a first liquid crystal panel 140, and a second liquid crystal panel 150. The backlight module includes a light guide plate 110, a light source 112, a transflector 116, a first set of optical films 120, and a second set of optical films 30.
The light guide plate 110 includes a first surface 110a, a second surface 110b, a third surface 110c, and a fourth surface 110d. The first set of optical films 120 includes a first diffuser 121, a first brightness enhancement film 122, a second brightness enhancement film 123, and a second diffuser 124. The second set of optical films 130 includes a third diffuser 131, a third brightness enhancement film 132, a fourth brightness enhancement film 133, and a fourth diffuser 134.
The light source 112 is disposed adjacent to the third surface 110c of the light guide plate 110. A light reflector 113 partially covers the light source 112. The first set of optical films 120 is disposed on the first surface 110a of the light guide plate 110. The transflector 116 and the second set of optical films 130 are sequentially disposed under the second surface 110b of the light guide plate 110. The first and second sets of optical films 120, 130 are used to improve the brightness and uniformity of the backlight module. A reflector 115 is adhered to the fourth surface 110d of the light guide plate 110.
The transflector 116 comprises a plurality of extremely thin layers. The layers comprise metal particles, and define minute holes or concavities therein. The transflector 116 thus enables the backlight module to emit light from two main sides thereof. The backlight module and the two liquid crystal panels 140, 150 form the double-sided LCD 100.
However the transflector 116 is generally an expensive component that increases the cost of the backlight module.
What is needed, therefore, is a less expensive backlight module.